1. Field of the Invention
The invention concerns a flow cell with a layered arrangement of three plates, in which an intermediate plate made of a flexible material is held between plates made of a more rigid material, and at least one of the plates has at least one recess for holding fluid, which recess is bounded by another plate of the layered arrangement.
2. Description of the Related Art
Miniaturized flow cells of this type are finding increasing use in analysis and sensor technology in the field of chemistry, especially biochemistry, and in medicine, especially diagnostics. The aforementioned recess can form, e.g., a microchannel, a reaction chamber with a fluid connection with the microchannel, and/or a chamber for holding a sensor, such that the dimensions of these recesses in at least one direction in space can vary between a few tens of micrometers to 100 micrometers. Depending on their construction and outfitting, flow cells of this type can completely or partially take over analyses performed in the laboratory as laboratory systems “on a chip”.
Especially in regard to medical applications, it is important to be able to mass-produce these kinds of flow cells with microstructures as inexpensively as possible. Expensive glass or silicon-like substrates that allow precise microengineering by semiconductor techniques must be reserved for parts of the flow cell for which plastics are out of the question due to their material properties.
Systems similar to the flow cell described above are disclosed by U.S. Pat. No. 4,798,706, WO 01/24933, WO 99/19717, U.S. Pat. No. 5,500,270, U.S. Pat. No. 5,571,410, U.S. Pat. No. 5,658,413, U.S. Pat. No. 5,738,825, and WO 99/46045.
The above-cited document WO 01/24933 describes a flow cell that consists of three components with an elastic intermediate plate, wherein the components are held together solely by the adhesion of the contacting surfaces.
A flow cell of the aforementioned type is described in U.S. Pat. No. 5,376,252. The intermediate plate, which is made of an elastic material, has channel structures. During the operation of the flow cell, the three components are pressed together by an external clamping device, so that liquid-tight microchannels are formed. After the flow cell has been removed from the external clamping device, the connection between the plates is broken, and this results in the risk of chemical and biological contamination of the environment. Before the plates are secured in the clamping device, extensive measures are necessary to align the functionally interacting microstructures on the plates with one another.